Data Hacking

Using a Signal Repeater
Chapter 4 — Antenna Hacks
Another way to bring a signal indoors — for example, into an office building in which you
want to set up a PC time sync system on each floor — is to use a GPS signal repeater.
GPS signal repeaters are also great idea on bigger yachts and boats too.
For specific information on splitters and repeaters, helpful websites include the following:
Coverage Solutions: www.coveragesolutions.net/gps.htm
GPS Source: www.gpssource.com
A GPS repeater kit usually consists of an amplifier with a power supply and a passive antenna
assembled on a mount for easy roof installation. The input from an active GPS roof antenna is
amplified and retransmitted into the building.
These kits usually have an indoor range of about 250 feet (80 meters) and are easy to fit.
Installing these kits is easy because they are packaged with everything you need. All the parts
are properly weatherproofed and all the attenuation measurements are predetermined. The
GPS repeater kits normally include a preassembled pedestal GPS amplifier antenna assembly.
This is mounted indoors in the room or building into which you want to bring a GPS signal.
The best placement is in a corner, about 8 to 30 feet (2.5 to 9 meters) high. This is then connected
via the GPS cable to the GPS roof antenna, which has been positioned in a suitable
spot. The amplifier antenna assembly is then used to retransmit the GPS signal within the
building. The repeater antenna can be adjusted for best coverage within the building.
Building Your Own Mega GPS Antenna
Before closing this chapter, let’s take a look at how you can create your own GPS quad-helix
antenna.
Materials
To build your GPS antenna, you need the following items:
Ground plane: This is the base of the antenna. For this you can use pretty much any
sheet metal you can find. Aluminum, brass, steel, and stainless steel all work equally well.
Thin (0.08 inch or 2 mm) sheet aluminum is probably the cheapest and best sheet to
use. Get a sheet approximately 12 inches (30 centimeters) square.
Helix coil tube: Two-inch diameter PVC pipe has a circumference of 7.4 inches (or 19
centimeters), which is to all intents and purposes an exact match of the GPS wavelength,
making it ideal for an antenna. Two-inch diameter gray plastic electrical conduit also has
these same dimensions, and while this costs a little more, it looks a little better.
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